Ships and offshore structures are supplied with lifeboats, capsules or other survival craft that can be used in an emergency to evacuate personnel from the vessel or structure. Such craft must be quickly accessible for use in case of an emergency. The craft have one or more release hooks used to support the craft from a davit. The davit includes cables and a winch mechanism that may be used to lower the craft to the water surface and raise the craft from the water. The release hook mechanism on the craft is normally operated when the craft is on the surface of the water. Since the release hook mechanisms are used infrequently, testing them periodically to determine that the release hooks are in operable condition is necessary. To insure operability, regulations require those release hook mechanisms be tested under no load and under an overload condition. It is current practice to simulate or launch the survival craft to determine that the release mechanism is operable under no load. To test under a load, it is current practice to place a load in the survival craft, lower the survival craft to a position just above the water surface and then operate the hook release mechanism on the craft.
A variety of models of davits and release hook mechanisms are approved for supporting the emergency craft. One hook is required on capsules, rescue boats and similar vessels and two hooks, which must release simultaneously, are required on lifeboats. The release lever mechanism for releasing the hooks is normally found inside the craft.
Regulations of the U.S. Coast Guard/Solas/IMO require that the release mechanism be tested once every five years. These regulations apply to U.S. and foreign flag vessels operating anywhere in the world. Many other countries also require that the support and release hook mechanism of the survival craft on their flag state vessels or structures in their territorial waters be periodically tested for operability. Resolution MSC 66/24 of the International Maritime Organization (IMO) requires that the release mechanism shall have two release capabilities: a normal release capability that will release a survival craft when it is waterborne (no load on the hooks) and an on-load release capability that will release the lifeboat with a load on the hooks. The on-load release capability should be demonstrated under any condition of loading from no load to a load of 1.1 (110%) times the total mass of the lifeboat when loaded with its full complement of persons and equipment.
There is need for a method and apparatus for testing the release hooks on capsules and similar vessels under a load required by regulations without launching the survival craft from the davit. Such a method and apparatus should make possible safer, less expensive testing and testing, if needed, more frequently. This will contribute to the safety and protection of life and property in sea operations.